Mitty

I would check your driveshaft. U-Joints will do that when they get dry and failing. Also the LS460 has a two piece driveshaft with a carrier midway. The carrier bearing will also cause this symptom when its failing. Do remember that you cant feel this by hand. They will be tight not loose. You will have to remove the shaft from the differential and go from there. If this is the case then I would recommend replacing all of them while you have the driveshaft out. You may be able to feel the carrier movement without removal of driveshaft. If it moves up and down and/or sideways, then its bad.